BRIEF DESCRIPTION OF PRIOR ART
Quick disconnect separable coupling elements which utilize a female socket which receives a disconnectable male element are utilized in pressurized lines employed for delivering fuel and the like. In many of these devices, the female socket is provided with a pair of ports or openings through the wall thereof at opposite sides of the socket, and a pair of latching handles are pivotally mounted on the sides of the socket body. Each handle includes a cam portion which projects through the opening into the interior of the socket for the purpose of engaging cam surfaces carried on the outer side of the male element which is to be engaged with the female socket. When the handles are pivoted to their latching positions, the cam surfaces carried on the handles engage the cam surfaces on the male element to force it into tight sealing contact with a gasket or sealing ring provided on an internal shoulder within the female socket element.
Patents which have previously been issued on quick connect couplings of the type described include U.S. Pat. No. 3,124,374 to Krapp, U.S. Pat. No. 3,195,934 to Parrish, U.S. Pat. No. 3,314,698 to Owens, U.S. Pat. No. 3,976,313 to Lauffenburger et al, U.S. Pat. No. 4,295,670 to Goodall, U.S. Pat. No. 2,033,142 to Lewis, U.S. Pat. No. 2,478,586 to Krapp, U.S. Pat. No. 2,518,026 to Krapp, U.S. Pat. No. 2,770,256 to Krapp, U.S. Pat. No. 2,770,474 to Krapp, and U.S. Pat. No. 3,860,274 to Ledstrom.
It is a general practice in constructing quick release couplings of the type described to pivotally hinge the cam arms or latching handles by the use of a hinge pin inserted through projecting bosses or ears on the side of the female socket element.
It has previously been recognized that vibration, or, occasionally, excessive pressure in the line which contains the coupling, or inadvertently directed mechanical forces, can cause the coupling to become disengaged or disconnected at a time when it is carrying high pressure fluid, or at other undesirable times. For the purpose of preventing such inadvertent or unintended decoupling of the quick disconnect coupling, which action is generally accompanied by undesirable pivotation to the unlatching position of the latching handles or cam arms, various types of safety latches or elements have been proposed for use in conjunction with the cam arm or latching handles. Thus, in U.S. Pat. No. 3,976,313 to Lauffenburger et al, it is proposed to provide spring biased ball elements which are mounted in ears adjacent the path of movement of the cam arms. The balls project into this path of movement, and in order to be by-passed by the cam arms during the unlocking or disengaging motion thereof, the balls must be pressed into the ears against the action of the springs with which they are in contact. This requirement that the balls be displaced from their normal, spring biased position against the force exerted thereon by the springs assures that a positive and intentional force of substantial mangnitude must be exerted upon the cam arms or latching handles in order to pivot them from the locking position, past the balls to the unlocking position.
Similar recognition of the problem of inadvertent, untimely decoupling of quick disconnect couplings of the type described is set forth in U.S. Pat. No. 4,295,670. This patent proposes to positively lock the latching handles in their latching positions by means of safety pins which are inserted through apertured lugs which are passed through openings in each handle intermediate its length. The pins thus occupy a blocking position preventing pivotation of the cam arms until the safety pins are pulled out of the retaining lugs. Of course, in one sense, an arrangement of this type where positioned pins provide a positive locking function which cannot be alleviated until the pins are pulled detracts or denigrates from the quick disconnecting criteria which is one of the features constituting a primary objective in the construction of such couplings.
In U.S. Pat. No. 3,314,698 to Owens, two methods are provided for retaining the cam arms carried on the coupling in a position which prevents their loosening due to vibration. In one of these, a simple ring is secured around each cam arm in a location where this ring is frictionally jammed into the slot into which the end portion of the respective cam arm pivots when the arm is moved to its locked position. This frictional jamming of the rings carried on the cam arms into such slots will then prevent the cam arms from falling free from their locking position under the influence of vibration.
In the second method proposed for preventing inadvertent loosening of the cam arms from their latching positions, a spring is provided on each of the cam arms. A medial part of the spring is coiled around the hinge pin which hingedly secures the cam arm to the female socket element. One end of this spring wire is then caused to bare against the outer side of the socket body, and the opposite end of the spring is secured to the free end of the cam arm so that pivotation of the cam arm from its latching to its unlatching position can be accomplished only by resiliently loading this spring in a compressed state in which its convolutions wrapped about the hinge pin are constricted. In other words, the wire spring is held under tension so that it constantly biases the cam arm toward the engaging or sealing position.
A problem posed by the wire spring safety element employed in the Owens patent is that the further the latching handle or cam arm is pivoted from its coupling toward its uncoupling position, the more highly loaded becomes the spring wire. The highest loading and most pronounced resilient deformation of this spring occurs at the time when the cam arm is pivoted to its fully open position. Thus, the spring exerts its highest return force on the arm in this position of the arm, and if the operator inadvertently releases the cam arm at this time, it will be rapidly and forceably returned to its locking position, thus posing some safety hazard to the operator.